Efficiency Analysis of a Hall Thruster Operating with Krypton and Xenon

Abstract

Krypton has recently become the focus of attention in the Hall thruster community because of its relatively large specific impulse compared with xenon and its potential to operate with comparable efficiencies. However, before krypton can be considered a viable propellant choice for missions, the performance gap between xenon and krypton must be reduced. A series of diagnostic measurements are taken for xenon and krypton propellant using the NASA-173Mv1 Hall thruster and the results are analyzed using a phenomenological performance model. The combined use of experiments and modeling enables a direct comparison of several efficiency components for each propellant to be made. With this method, it is possible to pinpoint the exact causes for the efficiency gap between xenon and krypton. It is also possible to see the effect of the magnetic field topology on Hall thruster performance and where gains are being made due to the magnetic field. Although there is a large series of competing components that differentiate krypton and xenon performance, the largest factors that dictate the efficiency difference between krypton and xenon are krypton's inferior propellant utilization and beam divergence. For xenon, the propellant utilization is 5-10% higher and the beam divergence efficiency is approximately 8% higher.